PML RARA (GENE REARRANGEMENT QUALITATIVE)

A positive PML‑RARA test means the PML and RARA genes are fused—usually from t(15;17)—confirming acute promyelocytic leukemia (APL). It directs urgent, specific therapy (e.g., all‑trans retinoic acid and arsenic) and indicates high early bleeding/DIC risk. Patients often respond well to targeted treatment but require close monitoring for treatment response and minimal residual disease to detect relapse.

The PML‑RARA quantitative PCR test detects and measures the PML‑RARA fusion gene transcript found in acute promyelocytic leukemia (APL). It confirms diagnosis, quantifies disease burden, and monitors minimal residual disease and treatment response with high sensitivity using blood or bone marrow samples. Serial PCR results help guide therapy decisions and detect early relapse by tracking changes in transcript levels.

The PML-RARA fusion gene, created by t(15;17) chromosomal translocation in acute promyelocytic leukemia, encodes an abnormal fusion protein that blocks normal retinoic acid receptor signaling. It represses transcription of genes required for myeloid differentiation, halting promyelocyte maturation, and acts dominantly to promote proliferation. It also disrupts PML nuclear bodies, impairing apoptosis and genomic stability, thereby driving leukemogenesis.

The PML‑RARA translocation is a balanced reciprocal translocation between chromosomes 15 and 17, designated t(15;17)(q24;q21). It fuses the PML gene on chromosome 15q24 with the RARA gene on chromosome 17q21, producing a PML‑RARA fusion protein that is the molecular hallmark of acute promyelocytic leukemia (APL) and drives its pathogenesis.

PML‑RARA arises from a reciprocal chromosomal translocation t(15;17) that fuses the PML gene on chromosome 15 with the RARA gene on chromosome 17. The PML‑RARA fusion protein disrupts retinoic acid receptor signaling and blocks differentiation of promyelocytes, causing accumulation of immature myeloid cells and precipitating acute promyelocytic leukemia. This abnormality is the defining molecular lesion in most cases.

A positive JC virus (JCV) antibody test indicates past exposure and the presence of antibodies. It does not mean active infection, but it raises the risk of progressive multifocal leukoencephalopathy (PML) with certain immunosuppressive or antibody therapies. Clinicians use the result for risk stratification, more frequent MRI monitoring, possible repeat testing, and to guide treatment choices.